This review highlights recent developments for on-line determination of residues and contaminants in complex matrices such as food samples. This involves the on-line coupling of a sample preparation technique (as the first "dimension") with a chromatographic system (second "dimension"), usually followed by mass spectrometry. Although frequently treated as quite distinct techniques, the role of all devices utilized as the first dimension in this approach aims to decrease the sample complexity while eliminating as much as possible the matrix contaminants to facilitate the qualitative and quantitative determination of the compounds of interest. This review will focus on the following techniques as the first dimension: (i) on-line solid-phase extraction; (ii) in-tube solid-phase microextraction; (iii) matrix solid-phase dispersion; and (iv) turbulent flow chromatography. The second dimension is usually performed using a chromatographic column to isolate the analyte(s) of interest for further mass spectrometry determination. A description of the basis of this on-line approach and its distinct set up possibilities is presented, which is followed by a critical review of the literature covering this subject in the last ten years (focusing on the last five years) with emphasis on the analysis of residue and contaminants in food samples.

1 Resistance development in pest insects has guided the advance of cleaner and more effective strategies for pest control. An interesting and promising strategy is the manipulation of insects via their gut microbiota. 2 To evaluate the feasibility of this strategy, Diabrotica speciosa, a highly polyphagous pest insect from South America that causes substantial damage to several important crops, was reared under controlled conditions. Aerobic culturable bacteria were isolated from the gut of D. speciosa and identified using proteomic fingerprints obtained by matrix-assisted laser desorption ionization coupled to time-of-flight mass spectrometry (MALDI-TOF MS), as well as by genomic methods via partial sequencing of the 16S rRNA gene. 3 Seventy-three strains belonging to 17 genera and up to 29 different species were isolated. -Proteobacteria of the orders Pseudomonadales and Enterobacteriales were the predominant. A core gut microbiome for the genus Diabrotica could be inferred when microbiotas from different species from the genus were compared. Molecular and spectrometric techniques indicated complete agreement of genera classification, although cluster analysis revealed distinct taxonomic grouping patterns. 4 MALDI-TOF MS provided reliable identification of culturable gut bacteria, demonstrating similar efficacy, with cheaper and faster results relative to partial 16S rRNA gene sequencing, and also showed an interesting and unexpected phyloproteomic correlation.

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Botanical extracts are a plentiful resource of molecules with different biological activities, such as insecticides and antimicrobial pesticides. In this context, the aim of this work was to evaluate the efficacy of botanical extracts from the Brazilian savannah against Diabrotica speciosa and bacterial strains isolated from the gut of this insect under aseptic conditions. The bacterial isolates were identified by genomic and proteomic approaches, and bioassayed against eighteen botanical extracts in vitro. The best results of bacterial inhibitions were obtained for the extracts of Casearia sylvestris and Psidium laruotteanum. Fractions of C. sylvestris and P. laruotteanum, quantitatively evaluated by chromatographic analyses, showed a relationship between the bactericidal activity and phytochemical profile. In vivo assays showed that P. laruotteanum was also effective for the control of D. speciosa. Those results show that selected natural products can have both antimicrobial and insecticidal activities.